Purpose To evaluate the effect on low preoperative corneal astigmatism of 3.0 mmon-axis clear corneal incision in phacoemusification.
Design Prospective study.
Methods The study evaluated 167 eyes of 149 cataract surgery candidates having preoperative corneal astigmatism≤1.0 diopter (D).3.0 mmclear corneal incision phacoemulsification was performed on the corneal steepest meridian in a right-handed approach. The eyes were grouped by incision location. The postoperative corneal astigmatic changes were calculated based on corneal topographic readings before surgery and along the 12-week follow-up postoperatively. The surgical induced astigmatism was calculated by Holladay-Cravy-Koch method.
Results 12 weeks postoperatively, the surgically induced astigmatism (magnitude) using superior or nasal incision was significantly greater than using temporal incision. With preoperative astigmatism of 0.12D to 0.38D, on-axis clear corneal incision at each site led to a significant increase in corneal cylinder and a marked rotation of corneal steepest meridian, whereas temporal incision resulted in the smallest postoperative corneal cylinder. With preoperative astigmatism of 0.5D to 1.0D, the approach reduced the preexisting corneal cylinder and resulted in similar postoperative corneal cylinder at all incision sites, yet the superior and nasal incision produced a significant axial rotation.
Conclusions For astigmatism correction,3.0 mmon-axis clear corneal incision phacoemusification is recommended with preoperative corneal astigmatism between 0.50D and 1.0 D at all incision sites. Temporal incision is recommended with negligible corneal astigmatism and nasal on-axis incision may be a feasible choice for a right-handed surgeon on some occasions. |
